We have studied the spatial and temporal development of photoreceptor-specific proteins in the macaque retina from early fetal life to adulthood. These include Red/Green (R/G) and Blue (B) opsin for cones; rhodopsin for rods; proteins involved in the visual phototransduction cascade such as transducin, rhodopsin kinase and phosphodiesterase; and the structural protein peripherin. Sequential waves of opsin expression move across the retina, beginning in the fovea at Fd66-70, with rhodopsin expressed first, biopsin slightly later (Fd70), and R/G opsin expressed last with a significant delay. Several tests of expression patterns suggest that each opsin is expressed independently of the others and does not influence neighboring photoreceptor opsin phenotypic choice. Peripherin is expressed at the same time as opsin in each cell type, consistent with its structural role in stabilizing the fluid outer segment (OS) membrane. Transduction cascade proteins appear shortly aft er R /G opsin, but 1-2 weeks after S opsin. All cones at a given point express transduction proteins at the same time, suggesting that some local signal initiates their expression and coordinates the onset of the dark current within cone neural circuits. FUNDING NIH grants RR00166, EY04536, EY07031 and EY01730, and a Kayser Award. Hendrickson, A., Sears, S., and Bumsted, K. Expression of photoreceptor-specific proteins in primate retina. Med. Sci. Monitor 4 11-16, 1998. Bumsted, K. and Hendrickson, A. Distribution and development of short-wavelength cones differ between Macaca monkey and human fovea. J. Comp. Neurol. 403 502-516, 1999.